초록 ▼

The present invention relates to a two-stage biofilter reactor system for removing nitrogenous compounds from a recirculating aquaculture system. The system includes a aerobic nitrification unit and a downstream anaerobic denitrification unit, wherein both units have a mobile bed of suspended media

The present invention relates to a two-stage biofilter reactor system for removing nitrogenous compounds from a recirculating aquaculture system. The system includes a aerobic nitrification unit and a downstream anaerobic denitrification unit, wherein both units have a mobile bed of suspended media whereon bacteria can grow and reduce nitrate and/or ammonia levels in the recirculating aquaculture system. Use of the two-stage system has the advantage of reducing the water exchange rates and consumption of salt when maintaining a saline effluent.

대표청구항 ▼

What is claimed is: 1. A recirculating aquaculture system comprising: an aquatic species rearing tank for holding fresh water or salt water effluent, an aerobic biofilter reactor in fluid communication with the rearing tank, wherein the aerobic biofilter reactor comprises a tank having an inlet and

What is claimed is: 1. A recirculating aquaculture system comprising: an aquatic species rearing tank for holding fresh water or salt water effluent, an aerobic biofilter reactor in fluid communication with the rearing tank, wherein the aerobic biofilter reactor comprises a tank having an inlet and an outlet for movement of the effluent therein, media means to support the growth of aerobic microorganisms active in nitrification suspended within the fresh water or salt water effluent, and aeration means to inject air or oxygen into the fresh water or salt water effluent for effective aerobic nitrification by the microorganisms; an anaerobic biofilter reactor in fluid communication with the aerobic biofilter reactor and positioned downstream from the aerobic biofilter reactor, wherein the anaerobic biofilter reactor comprises a tank having an inlet and outlet for movement of the effluent from the aerobic biofilter reactor therethrough, media means to support the growth of anaerobic microorganisms active in denitrification suspended within the fresh water or salt water effluent, and means for introducing a carbon source and optionally a nitrite source into the anaerobic biofilter reactor for effective denitrification by the microorganisms; and means for circulating effluent between the rearing tank and aerobic and anaerobic biofilter reactors, wherein the media means in the aerobic and anaerobic biofilter reactors is kept in motion within the fresh water or salt water effluent; wherein the recirculating aquaculture system is characterized by at least one of (a)-(d); (a) the media means in the aerobic and anaerobic biofilter reactor being fabricated from polyethylene and having a wheel shape with about a 10 mm diameter; (b) the aerobic biofilter reactor being fed daily with between 13% and 25% of system effluent; (c) the anaerobic biofilter reactor being fed daily with between 13% and 25% of system effluent after passing through the aerobic biofilter reactor; and (d) The aerobic and anaerobic biofilter reactors comprising up to about 60% to about 75% of its volume with the biomas carrier structures. 2. The recirculating aquaculture system according to claim 1, wherein the effluent is saltwater. 3. The recirculating aquaculture system according to claim 1, wherein the effluent is fresh water. 4. The recirculating aquaculture system according to claim 1, wherein the media means in the aerobic and anaerobic biofilter reactor is fabricated from polyethylene. 5. The recirculating aquaculture system according to claim 1, wherein the media means in the aerobic and anaerobic biofilter reactor is fabricated from polyethylene and having a wheel shape with about a 10 mm diameter. 6. The recirculating aquaculture system according to claim 1, wherein the anaerobic microorganisms comprise an anammox bacteria of the order Planctomycetes which is capable of anammox activity using nitrite in place of oxygen as the preferred electron acceptor and CO2 as a sole carbon source. 7. The recirculating aquaculture system according to claim 1, wherein the carbon source introduced into the anaerobic biofilter reactor is starch. 8. The recirculating aquaculture system according to claim 1, wherein the carbon source introduced into the anaerobic biofilter reactor is selected from the group comprising monosaccharides, oligosaccharides and polysaccharides. 9. The recirculating aquaculture system according to claim 1, wherein the aerobic biofilter reactor was fed daily with between 13% and 25% of system effluent. 10. The recirculating aquaculture system according to claim 1, wherein the anaerobic biofilter reactor was fed daily with between 13% and 25% of system effluent after passing through the aerobic biofilter reactor. 11. The recirculating aquaculture system according to claim 10, wherein the system effluent was retained from about an hour to about six hours to reduce concentration of nitrates in the system effluent. 12. The recirculating aquaculture system according to claim 1, the aerobic and anaerobic biofilter reactors comprise up to about 60 to about 75% of its volume with the biomass carrier structures. 13. A method for removing nitrogenous products from a recirculating aquaculture system, the method comprising: housing an aquatic species in a rearing tank containing fresh water or salt water effluent contaminated with ammonia; introducing and circulating the fresh water or salt water effluent into an aerobic biofilter reactor and treating the effluent with aerobic microorganisms active in nitrification for a sufficient time to reduce ammonia concentration and increase concentration of nitrates, wherein the microorganisms are positioned on media means to support the growth of the microorganisms and wherein the media means is suspended within the fresh water or salt water effluent, removing the nitrified fresh water or salt water effluent from the aerobic biofilter reactor and introducing same into an anaerobic biofilter reactor for treatment with anaerobic microorganisms active in denitrification for a sufficient time to reduce concentration of nitrates, wherein the microorganisms are positioned on media means to support the growth of the microorganisms and wherein the media means is suspended within circulating fresh water or salt water effluent; and introducing the denitrified effluent into the rearing tank; wherein said method is characterized by at least one of (a) and (b): (a) the biomass carrier structures in the aerobic and anaerobic biofilter reactors being kept in continuous motion at an effluent flow velocity of about 0.15 to about 2.00 cubic feet per second; and (b) introducing air/oxygen into the aerobic biofilter reactor, wherein the aerobic biofilter reactor comprises a dissolved oxygen concentration of about 4 to about 8 mg/l. 14. The method according to claim 13, wherein the denitrified effluent is passed through the aerobic biofilter reactor before reentry into the rearing tank. 15. The method according to claim 13, further comprising introducing a carbon source to the anaerobic biofilter reactor. 16. The method according to claim 13, further comprising introducing air/oxygen into the aerobic biofilter reactor. 17. The method according to claim 13, wherein the biomass carrier structures in the aerobic and anaerobic biofilter reactors are kept in continuous motion at an effluent flow velocity of about 0.15 to about 2.00 cubic feet per second. 18. The method according to claim 16, wherein the aerobic biofilter reactor comprises a dissolved oxygen concentration of about 4 to about 8 mg/l. 19. A recirculating aquaculture system including an aquaculture rearing tank coupled with a two-stage biofilter reactor assembly for removing nitrogenous compounds from a recirculating aquaculture medium, said two-stage bioreactor filter assembly including an aerobic nitrification unit and an anaerobic denitrification unit, wherein said anaerobic denitrification unit comprises microorganisms on support media comprising biomass carrier structures occupying at least 60% of the volume in said anaerobic denitrification unit, said microorganisms including at least one of: (a) Planctomycetes having anammox activity, and (b) Bacillus producing amylase. 20. The recirculating aquaculture system of claim 19, wherein said aquaculture rearing tank contains fish in an aquaculture medium therein.